Synthesis of some monocyclic analogues of mycophenolic acid via the Johnson ortho ester Claisen rearrangement

Meza-Aviña, Ma Elena; Ordóñez, Mario; Fernández‐Zertuche, Mario; Rodríguez‐Fragoso, Lourdes; Reyes‐Esparza, Jorge; Ríos-Corsino, Abril A. Martínez de los

doi:10.1016/j.bmc.2005.07.013

Cited by 12 publications

(5 citation statements)

References 47 publications

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“…When 14a was treated with a large excess amount of triethylorthoacetate (10 equiv.) and a catalytic amount of propionic acid in refluxing xylenes, the resulting mixed ketene acetal underwent [3,3] sigmatropic rearrangement in situ to deliver γ,δ‐unsaturated diester 15a as a single diastereomer about the double bond 13. Hitherto the route was facile and high yielding, although a further five steps proceeding through cyclic anhydride 16 were required to achieve target compound 1h following the previously described protocol.…”

Section: Resultsmentioning

confidence: 99%

Identification of the First Alkenyl Chiloglottone Congener

2012

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Orchids of the genus Chiloglottis rely on sexual deception to attract a male thynnine wasp, whereupon a courtship routine results in the deposition and transfer of pollinia and subsequent pollination of the orchid. The chemical cues responsible for this behavior were recognized as a new class of natural products and efforts to synthetically prepare them, to assist in structural identification and to aid in ecological studies, have been ongoing. Most recently the first alkenylated member of this class was proposed based on GC–MS analysis of a physiologically active compound present in an orchid extract. The current work reveals synthetic efforts that provide access to diastereomerically pure unsaturated chiloglottone analogues and in combination with laboratory‐based electrophysiological assays and field‐based studies have unambiguously allowed identification of 5‐allyl‐2‐ethyl‐1,3‐cyclohexanedione (1d, chiloglottone 4) as the first alkenyl congener in the chiloglottone family. Convergent synthetic approaches, involving copper(I)‐mediated conjugate addition to a glutaconic ester converging on cadmium‐mediated desymmetrization of cyclic anhydrides or a Johnson–Claisen rearrangement of a mixed ketene acetal provided the appropriately substituted δ‐keto acids suitable for carbocyclization to furnish the required chiloglottone analogues.

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Section: Resultsmentioning

confidence: 99%

Identification of the First Alkenyl Chiloglottone Congener

2012

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“…Thus, to avoid the formation of the undesired enolate, the sequence of the synthetic steps was changed: starting material 1 was first reduced to diol 3 , thus rendering its central proton non‐acidic. It was then followed by acetylation ( 4 ) and hydroboration ( 5 ), [16] and finally protection of the primary alcohol [17] . This pathway successfully led to the desired product 6 , which was later used as the substrate for the enzymatic hydrolysis step.…”

Section: Resultsmentioning

confidence: 99%

“…It was then followed by acetylation (4) and hydroboration (5), [16] and finally protection of the primary alcohol. [17] This pathway successfully led to the desired product 6, which was later used as the substrate for the enzymatic hydrolysis step. It should be noted that the hydroboration reaction afforded, in addition to the desired primary alcohol 5, also small amount (in Figure 2.…”

Section: Oxygen-substituted P1' Building Blocksmentioning

confidence: 99%

Optically Active Functionalized Building Blocks for Peptidyl Olefin Peptidomimetics

2021

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Peptidyl olefins can function as bio-active peptide isosteres or as intermediates in the synthesis of other peptidomimetics. We previously developed a stereoselective chemo-enzymatic approach to optically active C-terminal building blocks for the synthesis of peptidyl olefins. These building units include a sulfone functionality, to enable a Julia-Kocienski reaction with N-terminal aldehydes. Here, we extend this synthetic methodology to building blocks that are functionalized at their side chains with oxygen, nitrogen or halogen. The method features key enzymatic hydrolysis of prochiral diesters to the corresponding hydroxy esters, a step that introduces the optical activity. The ordering of the subsequent chemical reactions, either protection-methanolysis-functionalization or functionalization-methanolysis-protection, determines the absolute stereochemistry of the final building blocks.

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“…Despite the initial isolation of MPA from fermentation broth of Penicillium spp., the current commercial production of MPA and its derivatives is almost exclusively by chemical synthesis [6,9]. There are increasing interests in biological transformation of MPA.…”

Section: Introductionmentioning

confidence: 99%